1. Field of the Invention
The present invention relates to an external cover-cooled rotary electric machine and a casing that is used therein that allows a refrigerant to flow through an external cover to perform cooling, and particularly relates to a small, lightweight external cover-cooled rotary electric machine that is suitable for use in automobiles and to a casing that is used therein.
2. Description of the Related Art
In the conventional induction motor described in Patent Literature 1, for example, a stator core is held by a stator frame, the stator frame and a front-end end bracket being fitted together so as to be mated and then fastened using bolts, and the stator frame and a rear-end end bracket being fitted together so as to be mated and then fastened using bolts. A zigzag-shaped cooling medium passage is formed inside the stator frame in an axial direction of the electric motor. This cooling medium passage is configured by forming cavities that have openings on an end surface on a side near the front-end end bracket inside the stator frame when the stator frame is cast, and sealing those opening portions using a sealing member.
Patent Literature 1: Japanese Patent Laid-Open No. HEI 6-269143 (Gazette)
In conventional induction motors, because the cooling medium passage is configured by sealing the opening portions of the cavities that are formed on the stator frame using a sealing member, one problem has been that a sealing member is required, increasing the number of parts, and reducing ease of assembly.
Although the stator frame and the end brackets are fitted together so as to be mated, those mated interfitting portions are for positioning parts relative to each other in a radial direction. Because mated interfitting portions for positioning are generally constituted by shallow-based indentations and protrusions, the contribution of the mated interfitting portions to improvements in rigidity of the assemblage of the stator frame and the end brackets is small, making the rigidity of the assemblage insufficient. Thus, another problem has been that the stator frame is deformed due to vibration during movement, etc., and the cooling medium leaks out.